A higher order modulation technology is a technology introduced to improve a volume of transmitted data under the premise of not increasing transmission bandwidth. At a present stage, in a Long Time Evolution (LTE) technology, generally, the highest order of the higher order modulation technology is 64 quadrature amplitude modulation (64QAM). With the development of technologies, compared with current 64QAM, a theoretical gain of 256QAM is 33%. In a 256QAM scenario, each resource element (RE) can carry 8 bits of data, and by comparison, in a 64QAM scenario, each RE can carry only 6 bits of data. Therefore, in a same RE scenario, a volume of data that can be transmitted in 256QAM is increased by 33% when compared with a volume of data that can be transmitted in 64QAM.
The 3rd Generation Partnership Project (3GPP) specifies that both a base station side and a user equipment (UE) side store a mapping table. As shown in FIG. 1, the mapping table includes: a modulation and coding scheme (MCS) index (namely, IMCS), a modulation order, and a transport block size index (TBS Index) (namely, ITBS). The base station side notifies the UE by sending the IMCS, so that the UE selects a corresponding modulation order and transport block size index from the mapping table according to the IMCS, and performs subsequent data processing. As can be seen from the mapping table shown in FIG. 1, in the existing 3GPP specification, 256QAM is not supported. In FIG. 1, modulation order numbers 2, 4, and 6 represent QPSK, 16QAM, and 64QAM respectively.
In order to support 256QAM, in an existing technical solution, the mapping table is directly modified, a total quantity of IMCSes in the table shown in FIG. 1 still remains 32, and in the 32 modulation orders, some modulation orders are deleted and replaced by the newly added modulation order: 256QAM, so that the UE can transmit data by using the modulation order: 256QAM.
However, in the prior art, in a case in which the base station side provides a service to UE supporting 256QAM, a compatibility problem of UE not supporting 256QAM is not considered. As a result, in the prior art, a base station cannot provide a service to both the UE supporting 256QAM modulation and the UE not supporting 256QAM modulation; and one of the UEs cannot demodulate data sent by the base station due to an incompatibility issue.